Inhibition of acid corrosion of steel using cetylpyridinium chloride

The cationic surfactant cetylpyridinium chloride (CPC) showed high inhibition efficiency for the corrosion of low carbon steel in 1 M H2SO4. Electrochemical measurements were dedicated to test the performance of CPC at different concentrations and temperatures. CPC has a significant inhibiting effect on the corrosion of steel and protection efficiencies up to 97% were measured. The inhibitor shifted the corrosion potential in the cathodic direction. It was found that adsorption is consistent with the Bockris - Swinkels isotherm in the studied temperature range ( 30 - 60 degreesC). The negative values of the free energy of adsorption and the decrease in apparent activation energy in the presence of the inhibitor suggest chemisorption of the CPC molecule on the steel surface.